Technical Field
The present invention concerns a stranded tensioning wire severing apparatus for stranded tensioning wires of steel, in particular stranded tensioning wires of prestressed concrete structures such as for example pylons of wind power installations, which is adapted to sever a bundle comprising a plurality of stranded tensioning wires in one working operation.
Description of the Related Art
For reinforcing prestressed concrete structures, in particular in the field of prestressed concrete pylons, use is made of stranded tensioning wires which by applying a tensile force provide for tensioning and overall reinforcement of the building structure. Taking the example of wind power installations, those stranded tensioning wires are fixedly connected in the tensioned condition to the structure. In the case of wind power installations the fixed connection is achieved for example by the stranded tensioning wires being anchored to the foundation, in the condition of being combined together to form a bundle. Anchoring is preferably effected by the tensioned stranded tensioning wires being fixed by means of a tie anchor to the ceiling of the pylon basement. That fixing action is typically effected by the stranded tensioning wires, working in the pylon basement, being passed through a suitable opening in the basement ceiling, tensioned by a hydraulic ram device, and then fixed to the ceiling by means of a special anchor. Following the tensioning and fixing procedure, there is generally still an excess length of stranded tensioning wires of greater or lesser length, which hang down into the pylon basement from the ceiling thereof and from the fixing anchor. Those stranded tensioning wires which are always still in the form of a bundle have to be removed for reasons of working safety and for better access to the pylon basement.
As the stranded tensioning wires comprise high-strength material, in particular steel or a steel alloy, because of the mechanical demands thereon, severing of the stranded tensioning wires is technically demanding. Hitherto it has been necessary for the bundle of stranded tensioning wires to be severed by means of severing grinding machines. That involves a major generation of noise and sparking. In the state of the art that is perceived to be a disadvantage.
In the case of the stranded wire bundles which are involved here, the use of conventional stranded wire severing devices which are adapted to ‘nip or pinch off’ the stranded wires—this being shearing severing thereof—is not readily possible as such devices are only capable of severing individual stranded wires. The use of such devices would require the bundle of stranded wires to be unraveled and would necessitate the individual wires of the bundle being separated from each other to permit placement of the wire separating devices thereon. That has two further disadvantages: on the one hand the limited flexibility of the stranded wires means that a relatively large spacing is necessary relative to the anchor of the bundle of stranded wires in order to achieve the necessary separation of the individual wires. On the other hand, it is as good as impossible for all wires to be severed at the same level or in substantially the same cutting plane, whereby a large number of sharp-edged burrs occur at different heights in the pylon basement. Sealing off the severed stranded tensioning wires for the purposes of corrosion protection is also made difficult thereby. If sealing is intended by means of fitting a protective cap, that is sometimes impossible.
A further disadvantage that is encountered is that such a working operation is time-intensive.